Natural elements are the source of a vast supply of unused energy. The sun, wind, tides, ocean waves, and river currents, along with other natural phenomena, provide sufficient energy amounts to meet most energy needs. A difficulty resides in the fact that the energy from natural elements is not available upon demand. For example, wind power is available only when and where the wind is blowing.
Various devices have been proposed and used for deriving power from natural elements. For example, see U.S. Pat. No. 1,005,911 to Wilbur and U.S. Pat. No. 655,541 to Becker. In the former patent, water entrained with air is delivered by wave power to an underground cell where the water separates from the air and is there under pressure to perform a work function. Likewise, wave power is used in the latter patent to compress air for a work function. A problem exists in the storage of energy derived from machines which operate from natural elements. Compressed air is storable in tanks having a fixed volume. See U.S. Pat. No. 341,021 to Kierter. But such tanks are of limited capacity and the pressure of the air stored in the tank will vary according to the amount of air stored therein. Systems have been proposed for storage of air under pressure in natural formations under the surface of the earth. See U.S. Pat. No. 2,454,058 to Hays.